The present invention relates to the field of cutting, and is particularly concerned with cutting sheet material, generally in single plies, with a cutting wheel.
Automatically controlled cutting machines for cutting single or a few plies of sheet material are known in the prior art as illustrated in U.S. Pat. No. 3,522,753 issued to Schmied, U.S. Pat. No. 3,772,949 issued to Pavone et al. and U.S. Pat. No. 3,776,072 issued to Gerber et al. Typical of the types of sheet material cut in the prior art machines are limp sheet material such as woven and nonwoven fabrics, paper, leather, cardboard, foil and filamentary sheets or tapes.
Rotary wheel cutters in contrast to reciprocating blade cutters such as shown in U.S. Pat. No. 3,495,492 to Gerber et al. have unique characteristics which render them suitable for cutting single or relatively few plies of sheet material that collectively are relatively thin, for example, less than 1/4 inch (0.6 cm) in thickness. The cutting action produced by a wheel comes about through a severance of the material when the sharp peripheral cutting edge of the wheel is brought into engagement with a hard surface with the material in between. The edge severs the material or fibers in what is believed to be both a crushing and a cutting operation. Continuity of the support surface is therefore important. A unique and advantageous characteristic of the cutting process is that there is basically no inherent limitation on the speed at which the severance of material takes place nor upon the rate at which the cutting wheel operates in producing that severing process. Consequently, a cutting wheel is a desirable tool for cutting a single ply of a selected fabric material, for example, for a man's suit.
One of the principal difficulties that is encountered in cutting single plies of sheet material, however, is the retention of the sheet material in a fixed position throughout the cutting process. It will be understood that with an automatically controlled machine that operates from a predetermined program, the material cannot shift in the course of a cutting operation; otherwise, the pattern pieces that are cut will not conform to the programmed lines of cut. Also, since high speed is one of the main advantages of the cutting wheel, the machine should be designed to perform at high speed with minimum inertia and extra motion.
It is accordingly a general object of the present invention to provide an improved automatically controlled apparatus and process for cutting with a wheel without the difficiencies of the prior art.